mwave offers the Sans Digital TowerRAID 5-Bay eSATA / USB 3.0 Hard Drive Enclosure, model no. TR5UT+B, for $259.99 with free shipping. That’s the lowest total price we could find by $10. The enclosure comes with a 6GB PCI-Express controller card and holds five Serial ATA hard drives (up to 15TB total) configured as RAID 0, 1, 10, 3, or 5.
Note: It’s unclear from the manufacturer’s specifications if the controller card works with Macs.